Mexico City is one of several cities currently operating a license plate rationing strategy for transportation demand management. This has been predominantly a mechanism used in Latin American cities, including Bogota and Sao Paolo. License plate rationing is when access to certain areas--usually downtown cores--is restricted by the plate numbers on vehicles. For example, on Mondays cars with plates that end in a 5 or 6 cannot enter downtown. This policy is meant to primarily improve air quality, but also limit congestion and increase transit ridership.
Implemented in 1989, Hoy No Circulo was at first intended to last a single winter. However, with the incredible short term success experienced, the project was renewed and continues today. Much of the successes of the program rely on the steady enforcement in the restricted area with high fines and a substantial police presence. Much of the failures of the program, on the other hand, are due to the ability of the middle and upper classes to circumvent the restrictions and continue to act and drive as they have in the past.
The early success that Hoy No Circulo enjoyed addressed each of the goals set out for the program. During the winter of 1989 when the program was first initiated, Mexico City experienced a 20% decrease in daily vehicles circulating within the restricted areas and overall increases in vehicle speed within the restricted area, both signs of decreased congestion. There was also a decrease in fuel consumption in Mexico City during this time and a 6.6% increase in subway ridership, all statistics reported by Cambridge Systematics Inc (ES-1, 2).
Over the long term, however, these benefits proved unsustainable. Hoy No Circulo was founded on the principle that this strategy would lead to positive behavior changes. Like many transportation demand management strategies, this was the case for the pilot project, but once it became an adopted and ongoing policy many of the benefits disappeared. Middle and upper class drivers decided that transit was not an attractive long term option and the subway ridership increases seen in the first year of the program quickly returned to pre-policy levels. Now that the policy was adopted as a permanent condition, residents began buying secondary automobiles so they could drive downtown every day, regardless of the restrictions. Others found that since it was a once a week restriction, it was more convenient to switch to taxis and minibuses on the restricted days rather than take the light rail. Both of these new behaviors meant that there would be the same number of cars driving downtown, effectively eliminating any air quality improvements of the program. There has also been a noticeable decrease in air quality on Saturdays, when there are no restrictions. Overall, there has been no sustained improvement in air quality and no increase in transit ridership stemming from this program.
While the Hoy No Circulo is an innovative approach to transportation demand management, it has not been especially successful for Mexico City. Aside from the lack of sustained achievement, it has not been as equitable as originally posited. Upper and middle class households have been able to ignore the restrictions by purchasing a second vehicle or by purchasing new lower emission vehicles that were exempt from restrictions.
Mexico City has proposed expanding the program to include Saturday, imposing stricter emission standards, requiring mandatory busing for school trips and adding new cameras. These measures are implemented to tighten up the policy and better restrict vehicle access to downtown, but largely miss their mark in addressing the failures of the program thus far.
Data and statistics pulled from the Congestion Mitigation Commission Technical Analysis: License Plate Rationing Evaluation